/*    $OpenBSD: refill.c,v 1.8 2005/08/08 08:05:36 espie Exp $ */
/************************************************************************
 * Copyright (c) 1990, 1993
 *    The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Chris Torek.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 ************************************************************************/



#include "errno.h"
#include "stdio.h"
#include "stdlib.h"
#include "local.h"

static int
lflush(FILE *fp)
{
    if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
        return (__sflush_locked(fp)); /* ignored... */
    return (0);
}

/*
 * Refill a stdio buffer.
 * Return EOF on eof or error, 0 otherwise.
 */
int
__srefill(FILE *fp)
{

    /* make sure stdio is set up */
    if (!__sdidinit_flag)
        __sinit();

    fp->_r = 0;        /* largely a convenience for callers */

    /* SysV does not make this test; take it out for compatibility */
    if (fp->_flags & __SEOF)
    {
        errno = EEOF;
        return (EOF);
    }

    /* if not already reading, have to be reading and writing */
    if ((fp->_flags & __SRD) == 0) {
        if ((fp->_flags & __SRW) == 0) {
            errno = EBADF;
            fp->_flags |= __SERR;
            return (EOF);
        }
        /* switch to reading */
        if (fp->_flags & __SWR) {
            if (__sflush(fp))
                return (EOF);
            fp->_flags &= ~__SWR;
            fp->_w = 0;
            fp->_lbfsize = 0;
        }
        fp->_flags |= __SRD;
    } else {
        /*
         * We were reading.  If there is an ungetc buffer,
         * we must have been reading from that.  Drop it,
         * restoring the previous buffer (if any).  If there
         * is anything in that buffer, return.
         */
        if (HASUB(fp)) {
            FREEUB(fp);
            if ((fp->_r = fp->_ur) != 0) {
                fp->_p = fp->_up;
                return (0);
            }
        }
    }

    if (fp->_bf._base == NULL)
        __smakebuf(fp);

    /*
     * Before reading from a line buffered or unbuffered file,
     * flush all line buffered output files, per the ANSI C
     * standard.
     */
    if (fp->_flags & (__SLBF|__SNBF)) {
        /* Ignore this file in _fwalk to avoid potential deadlock. */
        fp->_flags |= __SIGN;
        (void) _fwalk(lflush);
        fp->_flags &= ~__SIGN;

        /* Now flush this file without locking it. */
        if ((fp->_flags & (__SLBF|__SWR)) == (__SLBF|__SWR))
            (void)__sflush(fp);
    }
    fp->_p = fp->_bf._base;
    fp->_r = (*fp->_read)(fp->_cookie, (char *)fp->_p, fp->_bf._size);
    fp->_flags &= ~__SMOD;    /* buffer contents are again pristine */
    if (fp->_r <= 0) {
        if (fp->_r == 0)
        {
            errno = EEOF;
            fp->_flags |= __SEOF;
        }
        else {
            fp->_r = 0;
            fp->_flags |= __SERR;
        }
        return (EOF);
    }
    return (0);
}
